<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        figure {
            display: flex;
            justify-content: space-between;
        }
        figure div {
            width: 3vw;
            height: 3vw;
            background-color: lightgreen;
            border-radius: 50%;
            margin: 0.2vw;
        }
         figure div:nth-child(2n+1) {
             background-color: red;
         }
    </style>
</head>
<body>
    <figure>
        <div></div>
        <div></div>
        <div></div>
        <div></div>
        <div></div>
        <div></div>
        <div></div>
        <div></div>
        <div></div>
        <div></div>
        <div></div>
        <div></div>
        <div></div>
        <div></div>
        <div></div>
        <div></div>
        <div></div>
        <div></div>
    </figure>
</body>
</html>